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A DYNAMIC POWER SAVING PROTOCOL FOR WIRELESS COMMUNICATION DEVICES

IP.com Disclosure Number: IPCOM000008351D
Original Publication Date: 1997-Sep-01
Included in the Prior Art Database: 2002-Jun-10
Document File: 3 page(s) / 196K

Publishing Venue

Motorola

Related People

Geoff Scotton: AUTHOR

Abstract

A method is presented to conserve battery life in a wireless communications device by dynamically adapting the power save protocol duty cycle to user trafftc demands and the power source capability.

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MO-LA Technical Developments

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A DYNAMIC POWER SAVING PROTOCOL FOR WI,RELESS COMMUNICATION DEVICES

by Geoff Scotton

  A method is presented to conserve battery life in a wireless communications device by dynamically adapting the power save protocol duty cycle to user trafftc demands and the power source capability.

1.0 INTRODUCTION

  Aself-powered battery operated communication device, such as a pager or wireless modem, typically utilizes a power saving protocol to conserve and extend the life of the device battery. The common principle of all such power saving protocols is to synchronize transmissions from a base station to a wireless subscriber device so that the transmissions occur while the destination device has its receive activated. As a consequence of synchronization delays message latency is compromised as some or all messages must be delayed until the next transmis- sion synchronization period occurs, thereby resulting in delays of many seconds to several minutes.

  The power saving protocols of some wireless networks, such as the DataTAC" Power-Save Protocol, permit the subscriber device .to negotiate the receiver duty cycle and hence the potential message latency.

  In this paper a method is presented for dynami- cally modifying the receiver duty cycle to optimize battery life and minimize message latency under a variety of device configuration and user traffic profile scenarios. Moreover it will be shown that this can be achieved without adding additional net- work trafilc overhead.

2.0 RECEIVER DUTY CYCLE CONSIDERATIONS

  Several factors need to be considered when designing the receiver duty cycle of a self-powered wireless communication device.

1. Customer battery life needs/expectations.
2. Battery capacity.
3. Availability of supplemental power sources.
4. User/subscriber device traffic profile.

2.1 CUSTOMER BATlEFlY LIFE MEDSKXPECTATIONS

  Fundamentally, after all the technical constraints and considerations have been brought to bear, the needs and expectations of the user regarding battery life are going to determine many aspects of the wireless communication product design. More specifically this will determine the minimum battery capacity that will be necessary to meet the product specifications. It is understood that this factor cannot be compromised and it exists as a constraint on all other design factors.

2.2 BAlTERY CAPACITY

  Determining the battery capacity requirements is achieved by matching the customer battery life needs/expectations and the device power consump- ti,on demands. In the sim~plest case this means designing the battery to meet worst case (continu- ous) receiverogerationwhile still meeting customer needs and expectations. While this may be appro- priate in some inst0nces it usually results in a case of overestimating the required battery capacity. This adds cost to the product and may make the product less attractive due to excess size and weight and potentially unsuitable for many applications. Actua...